(Bloomberg) -- Vinfast Auto Ltd. shares skyrocketed 109% to add $44 billion in market value to the Vietnamese electric vehicle maker on Tuesday, extending a raucous week since it went public.

The stock’s now 251% surge from an Aug. 15 debut has vaulted its market capitalization back above $84 billion, making its paper value much larger than General Motors Co. and Ford Motor Co. Tuesday’s rally came as more than 19 million shares changed hands, with investors flipping the stock that has a small portion of shares available for trading.

VinFast continues to be the top-performing company that went public via a special-purpose acquisition company merger this year, trading above $35 a piece after its tie-up with Black Spade Acquisition Co. Just 1.3 million shares are currently available for trading, meaning investors should brace for volatility as lower-float stocks are prone to see big swings. 

The jump in the share price gave a $20.1 billion boost to the wealth of the company’s chairman and founder, Pham Nhat Vuong. The wild moves in the shares, which Vuong controls 99% of, sent the fortune of Vietnam’s richest man careening from $21.2 billion on Friday to $43.4 billion today, according to the Bloomberg Billionaires Index.

Read more: Vietnam Tycoon Loses $23 Billion After Wild EV Stock Debut (2)

Additionally, many companies that merged with blank check firms have had rallies that fizzle out in the days and weeks after a deal closes, when the social media buzz subsides. De-SPACs that have made their debut this year have seen a median slump of about 45%, with 15 of them wiping out more than 80% of their value, according to data compiled by Bloomberg.

--With assistance from Tom Maloney.

(Updates share movement, value added throughout and adds detail on chairman’s wealth in penultimate paragraph)

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